The invention relates to a method and a gonioradiometer for the direction-dependent measurement of at least one photometric or radiometric characteristic of an optical radiation source.
Gonioradiometers are generally employed to measure photometric or radiometric characteristics of lamps and luminaires. These are opto-mechanical measurement systems, by means of which the directional dependence of variables for describing optical radiation is determined. By way of example, depending on the employed sensor or measuring instrument head it is possible to determine the luminous intensity distribution or the color distribution body of a light source. The centroid of the optical or radiation source to be tested is arranged in the rotational centre of the Gonioradiometer which corresponds to the coordinate origin of a spherical coordinate system. In this arrangement, photometric and radiometric characteristics can be measured goniometrically, i.e. for all directions of emission, by moving the optical or radiation source with respect to the sensor or by moving the sensor with respect to the optical or radiation source in the required angular ranges.
The photometric or radiometric characteristics of the source are determined by evaluating individual directions and/or by integrating the measurement results over portions or the whole solid angle of a distribution body.
A photometric or radiometric characteristic such as the luminous intensity of a light source is a direction-dependent variable, the emission direction of which can generally be specified by two angles in a coordinate system linked to the light source. In practice, the description by specific systems of planes has prevailed, said systems of planes being denoted A-planes, B-planes and C-planes. These planes are defined in the standard DIN 5032 part 1 (1999). A corresponding definition is also found in the document CIE No. 70 (1987): “The measurement of absolute luminous intensity distributions”, Central Bureau of the CIE, ISBN 3 900 734 05 4.
In practice, specific gonioradiometer types have proven their worth; these are likewise defined in DIN 5032 part 1 and in document CIE No. 70 (1987), the description of which is incorporated by reference. In particular, type 1.1 to 1.3 gonioradiometers, in which the light source is moved during a measurement while the sensor remains fixed, and type 4 gonioradiometers, in which the sensor is moved while the light source remains fixed, are of interest. In both cases, the light source or radiation source with its light centroid or radiation centroid is attached to the center of the gonioradiometer. A, B or C planes are measured, depending on the type of gonioradiometer. Lighting testing centers or laboratories must keep different gonioradiometers available in order to be able to serve all measurement objectives.
There is a need for a gonioradiometer for the direction-dependent measurement of at least one photometric or radiometric characteristic of an optical radiation source, which can easily realize different goniometer types and, accordingly, selectively detect measurement values in, e.g., A planes, B planes or C planes. Moreover, a corresponding method for the direction-dependent measurement of such characteristics of an optical radiation source is to be provided.